Providing an electric bus to local school district
How La Plata Electric Association (LPEA), located in Durango, Colorado, deployed an electrified school bus for safe and economical educational transportation.
Project overview
In 2021 La Plata Electric Association (LPEA) and Durango School District 9-R located in Durango, Colorado acquired an electric school bus and installed a vehicle–to–grid (V2G) capable DC fast charging station. LPEA funded the charging infrastructure and the difference in cost for the bus after grants. Durango School District 9-R agreed to allow remote management of their charging station and dispatch of their bus insofar as these activities do not interfere with their needs.
What challenge existed that the utility wanted to address?
LPEA is actively engaged with our school districts in V2G fleet electrification. We seek to model, sustain and scale a natural partnership between utilities and school districts while building out our own distributed resources. Through structured collaboration with shared benefits, funding for electric school bus fleets can be achieved in the long term. Establishing these partnerships based on mutual benefits will help our communities achieve a clean, healthy and affordable means of transporting school-age children. The project simultaneously contributes to our demand management and resilience goals and the creation of a community virtual powerplant.
- No cost recovery to scale bus deployments
- Health and safety risk from emissions
- Lack of a local resilience hub
What did the utility do to address the challenge?
We are performing timed charging and arbitrage using V2G. The peak demand avoided in our case is about $1,200 per bus per month in which we catch the peak. We are using this to fund the project and hope to prove out this means of fully electrifying local fleets of all kinds.
The buses have no tailpipe emissions and are healthy for children.
Buses can also be used as portable batteries capable of delivering energy to any building or community with bidirectional infrastructure. These could include things like Federal Emergency Management Agency shelters or communities isolated by fires. The ability to easily transport significant power supplies to critical locations provides flexible resilience.
Were alternatives considered? If so, what were they and why was the chosen project preferred?
At the time this project was executed in 2020 and 2021, there were no viable V2G chargers on the market but the BlueBird Nuvve partnership. We looked at another bus brands but based on our requirements this would be the only option. Then, the funding for this largely came through a Regional Air Quality Council grant for electric school buses. With that part of the money dedicated to the e-bus, we were able to fund the remainder and the infrastructure with the V2G pilot and offer the school a free bus.
How does the project advance decarbonization and/or energy equity?
The VPP is an expanding program. A comprehensive VPP program we are calling ‘Community Power’ will target all community levels, from institutional partners to members’ home devices.
How were communities involved in planning and/or implementation of the project?
LPEA was able to bring this school bus to Durango School district 9-R entirely free of charge. We did much of the up-front legwork on the grant and through covering the charging station, transformer and all associated construction. Because of the ease of implementation, the decision to accept the offer was easily made.
The community was involved at many levels including the training of the drivers, bus rides for city council, our state senator and countless children. Feedback has been consistently positive throughout the community. By serving kids, schools, the grid and our costs, this has been a project that everyone has been able to get behind. See linked media for some examples.
What has the utility learned through the project?
Charging and Electrical Service: We installed a 60 kW DCFC bidirectional charger and put in a transformer sized for three more of the same. We have found that about three to four years out is when it becomes worth it to replace a transformer vs upsize at the start like we did. Four buses is a projection of how many we thought might be in service by then.
Depending on route length and battery size it can be important to get a fast enough charger to do a full charge over lunch and go out again. Our 60 kW charger can fill its 155 kWh battery from zero in 2.5 hours. Some of the level 2 chargers could not accomplish this with longer routes. This is one area that’s worth doing the math on to ensure the bus will be sufficiently charged between its daytime routes.
Bidirectional charging: V2G has proven quite challenging in some areas. The brand-new technology has required significant software development with the charging company Nuvve to enable scheduling and successful dispatch. We have encountered issues such as BlueBird locking the ability to dispatch whenever the bus is at 75% charge or above. The second generation will also have a 155 kWh battery but will allow discharge from below 90%. This still requires careful timing and control of the after-school charge to ensure its capable of dispatching during evening peaks. Limiting the bus at all times is not a feasible solution due to the range already cutting it closer than the drivers like on extremely cold days.
V2G chargers that interface with buses are largely proprietary right now. For example, BlueBird only works with Nuvve for V2G. The buses can charge at any charging station open to the public but standards for bidirectional communication with vehicle telemetry have yet to be established and there is not cross compatibility yet.
Forecasting is required for a utility to realize the benefits of V2G but predicting our monthly coincidental peak has not been a major challenge.
Getting the dispatch software to work has taken lots of troubleshooting and development. However, we have had more and more successes as we make progress working with Nuvve. This is getting easier but has ongoing issues when it comes to predictably discharging as expected without a degree of active management.
We have had to work through billing nuances as well. We developed a custom contract with our district allowing us indefinite control of the buses charging in exchange for the up-front costs of the bus and charger. One of the big advantages of school buses is that pushing their charging into the late-night matches evening peaking utilities needs and lets the district benefit from off peak rates. If we charge after routes during the peak hours in order to dispatch on the 30-minute coincidental peak, by default we would charge them the on peak rate. We have hard coded their billing off peak but still must track dispatched energy.
Range: Range is an important factor for rural districts. I would take the kWh and assume you will get about 0.7 miles per. We have a 155 kWh battery and we see a bit over 110+ miles in good conditions. In extreme cold with the bus preheated at the charger we get about 75 miles. The district does 50-mile routes so this works, but it doesn’t give the drivers the security we would like.
We manage the bus charging and to date they have never once missed a route due to the state of charge being under 100%.
Maintenance: The bus started running routes in January of 2022 and has now operated for three semesters. So far, the standard upkeep has been extremely minimal as expected without the transmission, oil, engine, etc. However, it has broken three times, not from use, but from a combination of Cummins and Bluebird’s first-generation bugs. Twice it was towed to Denver for a few weeks and once they sent someone down and replaced the deep cycle battery here.
The 2nd generation buses are what people are buying today and what most Colorado schools receiving grants are going to be using. BlueBird learned a lot on the first round and we’re hopeful that they have worked out much of this.
What recommendations would you have to other utilities considering a similar project?
Despite the hurdles of pioneering this technology we remain bullish on school bus V2G. The timing and capability of the batteries to dispatch at 60 kW provides a powerful tool approaching the size of a utility scale battery when extended to an entire bus fleet. We are working with the district that acquired this bus on a grant application for another as we speak.
School buses match evening peaking utilities very well and have one of the best return on investments of any of LPEA’s controlled resources. City buses or regional transit buses can have evening routes that overlap the utilities peak. It’s critical to do route analysis on any buses to be sure they will be available with enough lead time to fill the battery prior to a peak event.
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